There are a few discrepancies between the OD matrices in the standard format (SiouxFalls/SiouxFalls_trips.tntp) and in the CSV format (SiouxFalls/CSV-data/SiouxFalls_od.csv). In particular, there is a difference of 100 demand between each of the following OD pairs, all symmetric:
4-11 and 11-4
9-15 and 15-9
10-11 and 11-10
11-18 and 18-11
12-20 and 20-12
13-24 and 24-13
I think the CSV file may have the origins and destinations interchanged: the original Sioux Falls trip table is almost symmetric, but not quite, and if you take the "transpose" of the CSV file you obtain the one in the TNTP file.